Modern day electronic systems are compact and often include one or more high-power, high-density devices, such as microprocessors. As the functionality of these microprocessors increases, they are becoming more dense, operating at higher speeds and are, thus, producing more heat. The heat-generating devices are typically incorporated into one or more integrated circuits. Each integrated circuit, or die, is housed in a relatively flat circuit package, or housing. As used hereinafter, the term "chip" refers to the circuit package and the included die.
The high-power, high-density chips frequently cannot be adequately cooled by the conventional forced air cooling system used to cool the overall electronic system. Instead, these chips require their own, i.e., dedicated, cooling systems.
One type of dedicated cooling system uses a liquid coolant that changes phase as it absorbs and dissipates heat. The coolant changes from liquid to vapor as heat is transferred to it from the chip, and changes from vapor back to liquid as it dissipates the heat to the surrounding environment.
The coolant may be housed in a conventional heat pipe, which has one end that acts as an evaporator and an opposing end that acts as a condenser. The end of the pipe which acts as the evaporator is placed in thermal contact with the chip and conducts heat, through its walls, from the chip to the coolant. This causes the coolant to vaporize. The vapor then travels to the condenser end of the pipe. At this end, heat is dissipated from the vapor to the surrounding environment and the vapor condenses. A wick or other capillary device draws the condensed coolant back through the pipe to the evaporator, where heat is again transferred to it from the chip.
Conventional heat pipes are relatively rigid and may include expandable bellows that are also relatively rigid. These heat pipes can be bent, but large bending radii are required and thick effective cross-sections result. These conventional heat pipes thus can not be readily deformed, either elastically or plastically, to match the space constraints of the electronic system. If the heat pipe is, for example, metal, it generally can not be flexed or bent, even to facilitate installation. Accordingly, accessible space within the system, that is the size and shape of the pipe and proximate to the heat-generating chip, must be created to accommodate the pipe. As consumers demand smaller, more powerful systems, providing space for these rigid heat pipes becomes more and more of a problem.
Components other than those incorporated into the relatively flat circuit housings, for example, power transistors, which are generally cylindrical, may also require cooling. The conventional, rigid heat pipes are not readily configurable, and thus, custom, shaped, pipes must be specifically manufactured for these components. Such custom pipes are generally more expensive to produce.
What is needed is a heat pipe that can fit into relatively narrow spaces and can be readily shaped, elastically or plastically, to conform to existing space within a system and/or to the components that are not incorporated into the circuit housings.
It is expected that the high-power chips will be included in more and more devices, to accommodate consumer demand for faster, more powerful electronic systems. Accordingly, heat pipes will be included in more and more of these systems. The cost of manufacture of these heat pipes thus becomes a significant factor in the cost of manufacture and the pricing of the systems. Thus, what is needed is a heat pipe that is inexpensive to manufacture.